Bifunctional tetrazole-carboxylate ligand based Zn(ii) complexes: synthesis and their excellent potential anticancer properties

An efficient one-pot synthesis of pyrazole complexes formed in situ: synthesis, crystal structure, Hirshfeld surface analysis and in vitro biological properties

The molecular crystals of monomeric and dimeric pyrazole complexes were prepared via one-pot syntheses. These are dichloridobis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.2/0.8), [Co0.20Zn0.80Cl2(C5H8N2)2] or [Co0.2Zn0.8Cl2(3,5-dmp)2] (1), and bis(μ-3,5-dimethyl-1H-pyrazole)-κ2N1:N2;κ2N2:N1-bis[bromido/chlorido(0.7/0.3)bis(3,5-dimethyl-1H-pyrazole-κN1)cobalt/zinc(0.1/0.9)], [Co0.20Zn1.80Br1.40Cl0.60(C5H7N2)2(C5H8N2)2] or [Co0.1Zn0.9Br0.7Cl0.3(μ-3,5-dmp)(3,5-dmp)]2 (2). The isolated complexes contain 3,5-dimethylpyrazole (3,5-dmp) ligands formed in situ from the decomposition of 1-hydroxymethyl-3,5-dimethylpyrazole. In both isolated complexes, some positional disorder is observed at the metal ions and halogen ligands. The molecular crystals of 1 and 2 are centrosymmetric, with the space groups C2/c and P-1, respectively. Additionally, in the dinuclear complex, the pyrazole ring has a bridging coordination function with respect to the metal ions. Both complexes have good biological activities against cancer cells. The results of an in vitro cytotoxicity study indicated that compounds 1 and 2 showed significant cytotoxicity for cancer cell lines, including hepatic (HepG2 cells), lung (A549 cells) and colon cancer cells (SW 480 and SW 620). Based on the calculated IC50 values against human cancer cell lines, it was found that both complexes demonstrated potent antiproliferative activity combined with great selectivity towards cancer cells. Complex 2 was a more effective cytotoxic agent which, at the same time, exhibited high cytocompatibility. The obtained data are very encouraging and could be useful for anticancer drug discovery.

A multi-spectroscopic and molecular docking approach for DNA/protein binding study and cell viability assay of first-time reported pendent azide bearing Cu(II)-quercetin and dicyanamide bearing Zn(II)-quercetin complexes

In the current study, one new quercetin-based Zn(II) complex [Zn(Qr)(CNNCN)(H2O)2] (Complex 1) which is developed by condensation of quercetin with ZnCl2 in the presence of NaN(CN)2 and Cu(II) complex [Cu(Qr)N3(CH3OH)(H2O)] (complex 2) which is developed by the condensation reaction of quercetin and CuCl2 in presence of NaN3, are thoroughly examined in relation to their use in biomedicine. The results of several spectroscopic studied confirm the structure of both the complexes and the Density Functional Theory (DFT) study helps to optimize the structure of complex 1 and 2. After completion of the identification process, DNA and Human Serum Albumin (HSA) binding efficacy of both the investigated complexes are performed by implementing a long range of biophysical studies and a thorough analysis of the results unveils that complex 1 has better interaction efficacy with the macromolecules than complex 2. The binding efficacy of complex 1 is comparatively higher towards both macromolecules because of its pure groove binding mode during interaction with DNA and the presence of an extra H-bond during connection with HSA. The experimental host-guest binding results is fully validated by molecular docking study. Interestingly complex 1 shows better antioxidant properties than complex 2, as well as quercetin, and it has strong anticancer property with minimal damage to normal cells, which is proved by the MTT assay study. Better DNA and HSA binding efficacy of 1 may be the reason for the better anticancer property of complex 1.